This invention relates to a group-supervisory apparatus for an elevator system wherein, among a plurality of cages in the elevator system, a service cage is selected for a hall call and assigned thereto, or it is caused to respond to a call or to stand by therefor.
In a case where a plurality of cages are juxtaposed, a group-supervisory operation is usually performed. One method of the group-supervisory operation is an assignment method, in which as soon as a hall call is registered, assignment estimation values are calculated for respective cages. The cage of the best estimation value is selected and assigned to serve the hall call. Only the assigned cage is caused to respond to the hall call to enhance operating efficiency and to shorten a hall wait time. In the group-supervisory elevator system of such an assignment method, arrival preannouncement lamps for the respective cages and in respective directions are usually disposed in the halls of individual floors to present the preannouncing displays of the assigned cages to users who are waiting in the halls. Therefore, the waiting users can wait for the cages in front of the preannouncement lamps without anxiety.
The assignment estimation values in the method of assigning the cage to the hall call as stated above, are calculated from the viewpoint of finding the optimal cage for allotting the hall call, assuming the present situation to proceed as it is. More specifically, the predictive values of the periods of time (hereinbelow, termed the "arrival expectation times") required for the cages to successively respond to calls and arrive at the halls of the floors are obtained on the basis of the positions and directions of the cages at the present time and the hall calls and cage calls presently registered. The periods of time (hereinbelow, termed the "continuation times") which lapsed since the registrations of the hall calls are obtained. The arrival expectation times and the continuation times are added to calculate the predicted wait times of all the hall calls presently registered. Then, the summation of the predictive wait times or the summation of the square values of the predictive wait times is set as each assignment estimation value. The hall call is allotted to the cage which exhibits the smallest assignment estimation value. With such a prior-art method, in allotting the hall call, whether the cage is optimal is determined on the basis of an extension line of the present situation, and hence, there has occurred the drawback that a hall call registered anew after the allotment becomes a long wait.
An example of the occurrence of the drawback will be explained with reference to FIGS. 12-15. In FIG. 12, letters A and B indicate cages No. 1 and No. 2, respectively, both of which are standing by in closed door states. It is assumed that, in such a situation, down calls 7d and 6d have been successively registered at the 7th floor and the 6th floor as shown in FIG. 13. According to the assignment estimation values of the prior-art assignment method, the down call 7d of the 7th floor is allotted to the cage A and the down call 6d of the 6th floor to the cage B to minimize the total wait time. Both the cages travel upwards, and change their directions at the 7th and 6th floors at nearly the same time.
If a down call at a floor above the 7th floor, for example, a down call 8d at the 8th floor is registered after the change in the directions, the down call 8d of the 8th floor becomes a rear call for either of the cages A and B. Regardless of the cage that the down call 8d is allotted to, a long time is taken before this call is serviced resulting in a long waiting time.
In contrast, assuming that the down call 7d of the 7th floor is allotted to the cage A, the down call 6d of the 6th floor is thereafter registered, and the call 6d is also allotted to the cage A, the situation becomes as illustrated in FIG. 14. Thus, even when the down call 8d of the 8th floor is registered nearly simultaneously, it does not require a long waiting time, since the cage B was standing by at the 1st floor and renders a direct travel service. In this manner, for the purpose of preventing the long wait, the hall calls need to be allotted so that the cages should not gather to one place, taking into consideration how the cages are arranged in the near future and even making allotments which lengthen the waiting time temporarily.
A so-called zone assignment method wherein a building is divided into a plurality of floor zones and wherein cages are assigned to the zones to serve hall calls is applied to the example stated above. Response to the hall calls is as shown in FIG. 15, and the down call 8d of the 8th floor is prevented from becoming the long wait. However, floors included in the individual zones are fixed, so that when a down call at the 5th floor, not the down call 6d of the 6th floor, has been registered by way of example, the down calls of the 7th and 5th floors are separately allotted to the respective cages A and B and the 8th-floor down call 8d becomes the long wait as shown in FIG. 14. Since, in this manner, the zone assignment method cannot flexibly cope with the registered situation of the hall calls, it still involves the problem that long waiting time arises.
An invention intended to solve this problem and disclosed in the official gazette of Japanese Patent application Publication No. 32625/1980 consists in an assignment method wherein, in order to prevent cages from gathering to one place and to enhance an operating efficiency likewise to the zone assignment method, when a hall call is registered, the cage scheduled to stop at a floor near the floor of the call is assigned thereto. Even in this assignment method, note is taken of the presence or absence of the cage scheduled to stop at the near floor. No judgement is made by properly grasping the changes of a cage arrangement with the lapse PG,7 of time, including the period of time which is required before the cage scheduled to stop arrives at the floor, how other hall calls are distributed and registered and when they will be responded to, what floors the other cages are on and which directions they are to be operated in, and so forth. Therefore, the problem of the occurrence of a long waiting time still remains.
Another method is disclosed in an invention disclosed in the official gazette of Japanese Patent application Publication No. 56076/1987 consists in an assignment method is shown wherein cages are caused to stand by at getting-off positions, so that when a hall call is registered anew, it is tentatively allotted to the respective cages in succession to expect the getting-off positions of the tentatively assigned cages, the degrees of dispersion of the cages are calculated from the expected getting-off positions of the tentatively assigned cages and the positions of the other cages. The degrees of dispersion are set as the estimation values of the respective cages so that the cage may be assigned more easily as the degree of dispersion is higher, whereby the cage to be assigned is determined from the estimation values of the cages. Thus, the cages fall into a dispersively arranged state even after a service to the hall call has ended, thereby to bring forth the great effect of saving energy owing to the prevention of the wasteful operations of unoccupied cages attributed to the dispersive standby, and also the effect that suspicions of building dwellers can be eliminated.
As obvious from its purpose, however, this assignment method is directed to the period of light traffic such as nighttime and is premised on a case where one hall call has been registered in the state in which all the cages are unoccupied and standing by. Therefore, this assignment method is not applicable to the allotment of hall calls under such a traffic condition that the hall calls are successively registered and that the cages are respectively traveling in response to the calls, and it has had the problem that long waiting times develop. Such a problem is caused by the fact that, since the method is intended to balance the arrangement of the unoccupied cages, the changes of cage positions with the lapse of time are not considered for the cages other than the tentatively assigned cage (in view of the premise of the method, the cage position changes of the other cages need not be considered), and the fact that the hall call allotment is determined with note taken of only the cage arrangement at the point in time at which a previous rider gets off the tentatively assigned cage (at that point of time, all the cages become unoccupied and fall into the standby states).